Scientists recreate the nuclear fusion reactions found inside stars

Scientists have, for the first time, recreated the extreme stellar plasma conditions of nuclear reactions found inside the hearts of stars.

Almost all of the heavier elements in the universe, including oxygen, are formed in nuclear reactions inside stars.

These reactions take place under incredibly high temperatures and pressures, making it nearly impossible for scientists to perform nuclear measurements in similar conditions – until now.

Experts in the fields of plasma physics, nuclear astrophysics and laser fusion have managed to perform experiments under just those conditions using incredibly powerful lasers.

Their experiments are the first thermonuclear measurements of nuclear reaction cross-sections, which help scientists measure the probability that a nuclear reaction will occur.

The cross-disciplinary collaborators were finding out how likely it was that the material inside of stars will undergo a fusion reaction to create heavier elements.

They used lasers to create high-energy-density plasma conditions equivalent to cores of stars up to 40 times more massive than the sun.

In the cores of these stars there are such extreme plasma conditions that temperatures can exceed 50 million Kelvin and such high pressure that isotopes of the lightest element in the universe, hydrogen, can be compressed by a factor of a thousand to near that of solid lead.

The work was conducted at the Lawrence Livermore National Laboratory’s National Ignition Facility (NIF), which is the only experimental tool in the world capable of creating these extreme conditions.

The NIF was used to drive an implosion in a gas-filled capsule, heating it to extraordinary temperatures and compressing it to a high density so that a fusion reaction could occur.

One of the most important findings is that we reproduced prior measurements made on accelerators in radically different conditions, said LLNL physicist Dan Casey, the lead author on the paper.

This really establishes a new tool in the nuclear astrophysics field for studying various processes and reactions that may be difficult to access any other way.

Perhaps most importantly, this work lays groundwork for potential experimental tests of phenomena that can only be found in the extreme plasma conditions of stellar interiors.

This work was conducted by researchers from LLNL, Ohio University, the Massachusetts Institute of Technology (MIT) and Los Alamos National Laboratory (LANL) and published in Nature Physics.